Methods and systems for maximum power point transfer in receivers

ABSTRACT

A MPPT management method in a receiver used for wireless power transmission may include the monitoring of the power extracted from RF waves at a dedicated antenna element in the receiver; detecting MPPT at an intelligent input boost converter in the receiver; comparing the detected MPPT with MPPT tables stored or calculated within a main system micro-controller in the receiver; adjusting the MPPT at the intelligent boost converter to find a suitable maximum peak that may enable an optimal power extraction from RF waves.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 14/272,207, filed on May 7, 2014, which is herein fullyincorporated by reference in its entirety for all purposes.

This application is related to U.S. patent application Ser. No.13/891,430, filed on May 10, 2013; U.S. patent application Ser. No.13/946,082, filed on Jul. 19, 2013; U.S. patent application Ser. No.13/891,399, filed on May 10, 2013; U.S. patent application Ser. No.13/891,445, filed on May 10, 2013; and U.S. patent application Ser. No.14/272,179, filed on May 7, 2014; U.S. Non-Provisional patentapplication Ser. No. 14/583,625, filed Dec. 27, 2014, entitled“Receivers for Wireless Power Transmission,” U.S. Non-Provisional patentapplication Ser. No. 14/583,630, filed Dec. 27, 2014, entitled“Methodology for Pocket-Forming,” U.S. Non-Provisional patentapplication Ser. No. 14/583,634, filed Dec. 27, 2014, entitled“Transmitters for Wireless Power Transmission,” U.S. Non-Provisionalpatent application Ser. No. 14/583,640, filed Dec. 27, 2014, entitled“Methodology for Multiple Pocket-Forming,” U.S. Non-Provisional patentapplication Ser. No. 14/583,641, filed Dec. 27, 2014, entitled “WirelessPower Transmission with Selective Range,” U.S. Non-Provisional patentapplication Ser. No. 14/583,643, filed Dec. 27, 2014, entitled “Methodfor 3 Dimensional Pocket-Forming,” all of which are incorporated hereinby reference in their entirety.

FIELD OF THE DISCLOSURE

The present disclosure generally relates to wireless power transmission,and more specifically to a MPPT management method to effectively improvepower extraction in receivers.

BACKGROUND

Wireless power transmission may be based on the extraction andconversion of power or energy from transmitted RF waves. One challengethat may be present during wireless power transmission is that power orenergy extracted from RF waves may be variable due to inherentcharacteristics of the medium and environment. Moreover, the power thatcan be extracted from RF waves may be zero at some instances of thewireless power transmission. The variability of the power extracted fromRF waves may be fueled by interference produced by electronic devices,walls, metallic objects, and electromagnetic signals, among others.

In order to extract suitable power from RF waves, it may be desirablethat a receiver may work as close as possible to maximum points orpeaks, despite the fact that external conditions may alter thetransmission of RF waves.

According to the foregoing, there may be a need to provide a methodand/or system for managing maximum power point tracking (MPPT) in areceiver capable of operating with a variable power source derived fromRF waves for powering and/or charging the batteries for a plurality ofelectronic devices.

SUMMARY

The present disclosure provides an MPPT management method for enabling areceiver to extract maximum power from RF waves.

The receiver may include components that may be required for theefficient wireless power transmission. In one embodiment, the receiversystem may include an intelligent input boost converter with a built-inmicro-controller operatively coupled with a main micro-controller todeliver continuous and suitable power or voltage to a load. The receivermay also include a dedicated antenna for measuring the power receivedfrom RF waves.

According to the disclosed MPPT management method, the built-inmicro-controller in the input boost converter may monitor the voltagelevels received at the main antenna array. Consequently, the built-inmicro-controller may detect the maximum power point by increasing ordecreasing the current it is taking from the main antenna array until ithas found a local power maximum. The built-in micro-controller in theintelligent input boost converter may send this MPPT data to the mainsystem micro-controller, which may compare the measured MPPT data withMPPT tables residing in the memory of main system micro-controller oruse it for further computation in algorithms located within the softwareof the main system micro-controller. The result from the tables oralgorithms may be used for adjusting the MPPT executed in theintelligent input boost converter for maximizing power extraction fromreceived RF waves.

Numerous other aspects, features, and benefits of the present disclosuremay be made apparent from the following detailed description takentogether with the drawing figures, which may illustrate the embodimentsof the present disclosure, incorporated herein for reference.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure can be better understood by referring to thefollowing figures. The components in the figures are not necessarily toscale, emphasis instead being placed upon illustrating the principles ofthe disclosure. In the figures, reference numerals designatecorresponding parts throughout the different views.

FIG. 1 illustrates wireless power transmission using pocket forming,according to an embodiment.

FIG. 2 illustrates a block diagram of a wireless power transmitter,which may be used in wireless power transmission, according to anembodiment.

FIG. 3 depicts a block diagram of wireless power receiver configurationthat may be used for extracting and converting power from transmitted RFwaves, according to an embodiment.

FIG. 4 illustrates the MPPT of characteristic curves, which may be usedto change the voltage direction and adjust the operation of thereceiver, according to an embodiment.

FIG. 5 shows a flowchart for the method enabled by the proprietary MPPTalgorithm controlling maximum power point transfer and operation of theinput boost converter, according to an embodiment.

DETAILED DESCRIPTION

The present disclosure is here described in detail with reference toembodiments illustrated in the drawings, which form a part here. Otherembodiments may be used and/or other changes may be made withoutdeparting from the spirit or scope of the present disclosure. Theillustrative embodiments described in the detailed description are notmeant to be limiting of the subject matter presented here.

As used here, the following terms may have the following definitions:

“Pocket-forming” refers to generating two or more RF waves that convergein 3-d space, forming controlled constructive and destructiveinterference patterns.

“Pockets of energy” refers to areas or regions of space where energy orpower may accumulate in the form of constructive interference patternsof RF waves.

“Transmitter” refers to a device, including a chip which may generatetwo or more RF signals, at least one RF signal being phase shifted andgain adjusted with respect to other RF signals, substantially all ofwhich pass through one or more RF antenna such that focused RF signalsare directed to a target.

“Receiver” refers to a device which may include at least one antenna, atleast one rectifying circuit, at least one input boost converter, atleast one storage element, at least one output boost converter, at leastone switch, and at least one communication subsystem for powering orcharging an electronic device using RF waves.

“MPPT or Maximum Power Point Tracking” refers to an algorithm includedin micro-controllers of a receiver for extracting maximum availablepower from RF waves.

FIG. 1 illustrates a wireless power transmission 100 usingpocket-forming. A transmitter 102 may transmit controlled RadioFrequency (RF) waves, which may converge in 3-d space. These RF waves104 may be controlled through phase and/or relative amplitudeadjustments to form constructive and destructive interference patterns(pocket-forming). Pockets of energy 106 may be formed at constructiveinterference patterns and can be 3-dimensional in shape, whilenull-spaces may be generated at destructive interference patterns. Areceiver 108 may then utilize pockets of energy 106 produced bypocket-forming for charging or powering a cordless electronic device110, for example, a smartphone, a tablet, a laptop computer (as shown inFIG. 1), a music player, an electronic toy, and the like. In someembodiments, there can be multiple transmitters 102 and/or multiplereceivers 108 for powering various electronic devices 110 at the sametime. In other embodiments, adaptive pocket-forming may be used toregulate the power transmitted to electronic devices 110.

FIG. 2 illustrates the block diagram of transmitter 102, which may beused in wireless power transmission 100. Transmitter 102 may include ahousing 202, at least two or more antenna elements 204, at least one RFintegrated circuit (RFIC) 206, at least one digital signal processor(DSP) or micro-controller 208, and one communications component 210.Housing 202 can be made of any suitable material which may allow forsignal or wave transmission and/or reception, for example plastic orhard rubber. Antenna elements 204 may include suitable antenna types foroperating in frequency bands such as 900 MHz, 2.5 GHz or 5.8 GHz asthese frequency bands conform to Federal Communications Commission (FCC)regulations part 18 (Industrial, Scientific and Medical equipment).Antenna elements 204 may include vertical or horizontal polarization,right hand or left hand polarization, elliptical polarization, or othersuitable polarizations as well as suitable polarization combinations.Suitable antenna types may include, for example, patch antennas withheights from about ⅛ inch to about 8 inches and widths from about ⅛ inchto about 6 inches. Other antenna elements 204 types that can be usedinclude meta-materials based antennas, dipole antennas, and planarinverted-F antennas (PIFAs), among others.

RF integrated circuit (RFIC) 206 may include a proprietary chip foradjusting phases and/or relative magnitudes of RF signals, which mayserve as inputs for antenna elements 204 for controlling pocket-forming.These RF signals may be produced using a power source 212 and a localoscillator chip (not shown) using a suitable piezoelectric material.Micro-controller 208 may then process information sent by receiver 108through communications component 210 for determining optimum times andlocations for pocket-forming. Communications component 210 may be basedon standard wireless communication protocols, which may includeBluetooth, Wi-Fi or ZigBee. In addition, communications component 210may be used to transfer other information such as an identifier for thedevice or user, battery level, location or other such information. Othercommunications component 210 may be possible, including radar, infraredcameras or sound devices for sonic triangulation of electronic device110 position.

FIG. 3 shows a block diagram of receiver configuration 300 which can beused for wireless powering or charging one or more electronic devices110 as exemplified in wireless power transmission 100. According to someaspects of this embodiment, receiver 108 may operate with the variablepower source generated from transmitted RF waves 104 to deliver constantand stable power or energy to electronic device 110. In addition,receiver 108 may use the variable power source generated from RF waves104 to power up electronic components within receiver 108 for properoperation.

Receiver 108 may be integrated in electronic device 110 and may includea housing (not shown in FIG. 3) that can be made of any suitablematerial to allow for signal or wave transmission and/or reception, forexample plastic or hard rubber. This housing may be an external hardwarethat may be added to different electronic equipment, for example in theform of cases, or can be embedded within electronic equipment as well.

Receiver 108 may include an antenna array 302 which may convert RF waves104 or pockets of energy 106 into electrical power. Antenna array 302may include one or more antenna elements 304 coupled with one or morerectifiers 306. RF waves 104 may exhibit a sinusoidal shape within avoltage amplitude and power range that may depend on characteristics oftransmitter 102 and the environment of transmission. The environment oftransmission may be affected by changes to or movement of objects withinthe physical boundaries, or movement of the boundaries themselves. It isalso affected by changes to the medium of transmission; for example,changes to air temperature or humidity. As a result, the voltage orpower generated by antenna array 302 at the receiver 108 may bevariable. As an illustrative embodiment, and not by way of limitation,the alternating current (AC) voltage or power generated by antennaelement 304 from RF waves 104 or pocket of energy 106 may vary fromabout 0 volts or 0 watt to about 5 volts at 3 watts.

Antenna element 304 may include suitable antenna types for operating infrequency bands similar to the bands described for transmitter 102 fromFIG. 2. Antenna element 304 may include vertical or horizontalpolarization, right hand or left hand polarization, ellipticalpolarization, or other suitable polarizations as well as suitablepolarization combinations. Using multiple polarizations can bebeneficial in devices where there may not be a preferred orientationduring usage or whose orientation may vary continuously through time,for example electronic device 110. On the contrary, for devices withwell-defined orientations, for example a two-handed video gamecontroller, there might be a preferred polarization for antennas whichmay dictate a ratio for the number of antennas of a given polarization.Suitable antenna types may include patch antennas with heights fromabout ⅛ inch to about 6 inches and widths from about ⅛ inch to about 6inches. Patch antennas may have the advantage that polarization maydepend on connectivity, i.e. depending on which side the patch is fed,the polarization may change. This may further prove advantageous asreceiver 108 may dynamically modify its antenna polarization to optimizewireless power transmission 100.

Rectifier 306 may include diodes or resistors, inductors or capacitorsto rectify the AC voltage generated by antenna element 304 to directcurrent (DC) voltage. Rectifier 306 may be placed as close as istechnically possible to antenna element 304 to minimize losses. In oneembodiment, rectifier 306 may operate in synchronous mode, in which caserectifier 306 may include switching elements that may improve theefficiency of rectification. As an illustrative embodiment and not byway of limitation input boost converter 308 may operate with inputvoltages of at least 0.6 volts to about 5 volts to produce an outputvoltage of about 5 volts. In addition, input boost converter 308 mayreduce or eliminate rail-to-rail deviations and may operate as a step-upDC-to-DC converter to increase the voltage from rectifier 306 to avoltage level suitable for proper operation of receiver 108. In oneembodiment, intelligent input boost converter 308 may exhibit asynchronous topology to increase power conversion efficiency.

As the voltage or power generated from RF waves 104 may be zero at someinstants of wireless power transmission 100, receiver 108 can include astorage element 310 to store energy or electric charge from the outputvoltage produced by input boost converter 308. In this way, storageelement 310 may deliver a constant voltage or power to a load 312 whichmay represent the battery or internal circuitry of electronic device 110requiring continuous powering or charging. For example, load 312 may bethe battery of a mobile phone requiring constant delivery of 5 volts at2.5 watts.

Storage element 310 may include a battery 314 to store power or electriccharge from the voltage received from input boost converter 308. Battery314 may be of different types, including but not limited to, alkaline,nickel-cadmium (NiCd), nickel-metal hydride (NiHM), and lithium-ion,among others. Battery 314 may exhibit shapes and dimensions suitable forfitting receiver 108, while charging capacity and cell design of battery314 may depend on load 312 requirements. For example, for charging orpowering a mobile phone, battery 314 may deliver a voltage from about 3volts to about 4.2 volts.

In another embodiment, storage element 310 may include a capacitor (notshown in FIG. 3) instead of battery 314 for storing and deliveringelectrical charge or power to load 312. As a way of example, in the caseof charging or power a mobile phone, receiver may include a capacitorwith operational parameters matching the load device's powerrequirements.

Receiver 108 may also include an output boost converter 316 operativelycoupled with storage element 310 and input boost converter 308, wherethis output boost converter 316 may be used for matching impedance andpower requirements of load 312. As an illustrative embodiment, and notby way of limitation, output boost converter 316 may increase the outputvoltage of battery 314 from about 3 or 4.2 volts to about 5 volts whichmay be the voltage required by the battery 314 or internal circuitry ofa mobile phone. Similarly to input boost converter 308, output boostconverter 316 may be based on a synchronous topology for enhancing powerconversion efficiency.

Storage element 310 may provide power or voltage to a communicationsubsystem 318 which may include a low-dropout regulator (LDO 320), amain system micro-controller 322, and an electrically erasableprogrammable read-only memory (EEPROM 324). LDO 320 may function as a DClinear voltage regulator to provide a steady voltage suitable for lowenergy applications as in main system micro-controller 322. Main systemmicro-controller 322 may be operatively coupled with EEPROM 324 to storedata pertaining the operation and monitoring of receiver 108. Mainsystem micro-controller 322 may also include a clock (CLK) input andgeneral purpose inputs/outputs (GPIOs).

In one embodiment, intelligent input boost converter 308 may include abuilt-in micro-controller (not shown in FIG. 3) operatively coupled witha main system micro-controller 322. The main system micro-controller 322may actively monitor the overall operation of receiver 108 by taking oneor more power measurements 326 (ADC) at different nodes or sections asshown in FIG. 3. For example, main system micro-controller 322 maymeasure how much voltage or power is being delivered at rectifier 306,input boost converter 308, battery 314, output boost converter 316,communication subsystem 318, and/or load 312. Main systemmicro-controller 322 may communicate these power measurements 326 toload 312 so that electronic device 110 may know how much power it canpull from receiver 108. In another embodiment, main systemmicro-controller 322, based on power measurements 326, may control thepower or voltage delivered at load 312 by adjusting the load currentlimits at output boost converter 316.

Main system micro-controller 322 may monitor the voltage levels at theoutput of the main antenna array 302 using ADC node point 307.

In another embodiment, main system micro-controller 322 may regulate howpower or energy can be drained from storage element 310 based on themonitoring of power measurements 326. For example, if the power orvoltage at input boost converter 308 runs too low, then main systemmicro-controller 322 may direct output boost converter 316 to drainbattery 314 for powering load 312.

Yet in another embodiment, receiver 108 may have a dedicated antennaelement 330 operatively coupled with a corresponding rectifier 332,where these dedicated antenna element 330 and rectifier 332 may be usedfor continuously monitoring the surrounding pocket of energy 106. Thisdedicated antenna element 330 may be separate from the main antennaarray 302. More specifically, the main system micro-controller 322 maymeasure power level at ADC node point 334 to compare against actual DCpower levels extracted from the receiver 108 system.

Receiver 108 may include a switch 328 for resuming or interrupting powerbeing delivered at load 312. In one embodiment, main systemmicro-controller 322 may control the operation of switch 328 accordingto terms of services contracted by one or more users of wireless powertransmission 100 or according to administrator policies.

FIG. 4 illustrates a graph 400, depicting the intensity (I) of currentavailable from main antenna array, (P) the power available from mainantenna array, and (V) the voltage from main antenna array. FIG. 4 showsa current-to-voltage curve 402 that may be obtained from receiver 108operation and which may vary according to the characteristics ofreceiver 108. FIG. 4 also shows a corresponding power curve 404 whichmay represent the power available (current×voltage) from the mainantenna array 302.

In one embodiment, voltage levels measured at ADC node point 307 may notnecessarily exhibit a linear relationship with the available currentfrom the main antenna array 302. Thus, power curve 404 may have multiplelocal peaks, including a global power maximum 406 at P1, and a localpower maximum 408 at P2.

The MPPT algorithm running in the input boost converter 308 maycontinuously track for a global power maximum 406 in graph 400, so thatinput boost converter 308 may be able to extract the maximum amount ofpower from antenna array 302. However, in some circumstances, the MPPTalgorithm may be stuck at a local power maximum 408 which may notcorrespond to the global power maximum 406 in graph 400. When operatingat a local power maximum 408, intelligent input boost converter 308 maynot be able to maximize the amount of power that can be extracted fromantenna array 302.

It may be an object of embodiments described herein to adjust the MPPTalgorithm to control the operation of intelligent input boost converter308 so that it can continuously operate at global power maximum 406 tomake the best use of the power that can be extracted from antenna array302 in receiver 108 system.

FIG. 5 shows a MPPT management method 500 that may be used formaximizing the amount of power that can be extracted from antenna array302 to deliver continuous and suitable power to receiver 108.

At monitoring step 502, the built-in micro-controller in the intelligentinput boost converter 308 may monitor voltage from antenna array 302 andsearch for a global power maximum 406 or local power maximum 408.

At step 504, the main system micro-controller 322 may read the resultfrom the input boost converter 308 or use ADC node point 307 toestablish the input boost converter 308 current operational MPPT.Subsequently, at step 506, the main system micro-controller 322 may readthe voltage of dedicated antenna element 330 at ADC node point 334. Atstep 508, the combination of the input boost converter 308 MPP and theoutput value of dedicated antenna element 330 may be used to eitherindex a predefined look-up table or be used in an algorithm. This resultmay or may not require an adjustment of the operational input parametersof the input boost converter 308 MPPT algorithm. Once action isdetermined, the main system micro-controller 322 may adjust the MPPTalgorithm executed by input boost converter 308, thus moving theoperation of input boost converter 308 from local power maximum 408 P2to global power maximum 406 P1, at step 510.

The predefined MPPT tables may include a characterization of a pluralityof receivers 108 in terms of ability to extract power from a particularfield. For example, the capability of receiver 108 for extracting powerfrom RF waves 104 may vary according to the configuration of antennaarray 302. In one embodiment, these MPPT tables may be determined bylaboratory measurements of different receivers 108 in a way that aparticular receiver 108 may be mapped to an optimal MPPT.

In one embodiment, main system micro-controller 322 may use theinformation contained in MPPT tables to provide initial conditions forrunning an optimal MPPT at intelligent input boost converter 308according to the specific characteristics or configuration of receiver108.

While various aspects and embodiments have been disclosed, other aspectsand embodiments may be contemplated. The various aspects and embodimentsdisclosed here are for purposes of illustration and are not intended tobe limiting, with the true scope and spirit being indicated by thefollowing claims.

What is claimed is:
 1. A receiver for charging a device utilizing powertransmission waves received at a plurality of antennas, the receivercomprising: a first rectifier coupled to a first antenna element andconfigured to rectify a first enemy received at the first antennaelement; a second rectifier coupled to a second antenna element andconfigured to rectify a second energy received at the second antennaelement; an input boost converter coupled to the second rectifier andconfigured to adjust the second energy rectified by the secondrectifier; and a controller coupled to the first rectifier and the inputboost converter, wherein the controller is configured to compare anavailable energy at the first rectifier with an energy received from thesecond rectifier via the input boost converter, and transmit anoperational instruction to the input boost converter to adjust theenergy rectified by the second rectifier.
 2. The receiver according toclaim 1, further comprising a plurality of antenna elements configuredto receive a plurality of wireless power transmission signal waves. 3.The receiver according to claim 1, wherein the input boost converter isfurther configured to determine at least one of a global power maximumand a local power maximum produced in the second rectifier.
 4. Thereceiver according to claim 1, wherein the controller is furtherconfigured to determine a maximum power point (MPP) value from thesecond rectifier via the input boost converter.
 5. The receiveraccording to claim 1, wherein the input boost converter comprises asecond controller coupled to the controller.
 6. The receiver accordingto claim 1, wherein the operational instruction comprises data toconfigure the input boost converter to further step up the energyrectified by the first rectifier to a global power maximum.
 7. Thereceiver according to claim 4, wherein the controller is configured toindex the MPP value in a look-up table.
 8. The receiver according toclaim 4, wherein the controller is configured to compare an availableenergy to the MPP value to determine the operational instructionthereby.
 9. The receiver according to claim 8, further comprising anoutput boost converter, wherein the controller is configured todetermine a load requirement for the receiver, wherein the controller isconfigured to control an operation of at least one of the input boostconverter and the output boost converter based on the load requirement.10. A method for charging a device utilizing power transmission wavesreceived at a plurality of antennas of a receiver, the methodcomprising: rectifying, by a first rectifier of a receiver, a firstenemy received at a first antenna element coupled to the firstrectifier; rectifying, by a second rectifier of the receiver, a secondenemy received at a second antenna element coupled to the secondrectifier; adjusting, by an input boost converter of the receiver andcoupled to the second rectifier, the second enemy rectified by thesecond rectifier; and comparing, by the receiver, an available energy ata first rectifier with an energy received from a second rectifier via aninput boost converter; and transmitting, by the receiver, an operationalinstruction to the input boost converter to adjust the energy rectifiedby the second rectifier.
 11. The method according to claim 10, furthercomprising stepping up, by the input boost converter, the energyrectified by the second rectifier.
 12. The method according to claim 10,further comprising determining, by the receiver, at least one of aglobal power maximum and a local power maximum produced in the secondrectifier.
 13. The method according to claim 10, further comprisingdetermining, by the receiver, a maximum power point (MPP) value from thesecond rectifier via the input boost converter.
 14. The method accordingto claim 10, wherein the input boost converter comprises a secondcontroller coupled to the controller.
 15. The method according to claim13, wherein the operational instruction comprises data to configure theinput boost converter to further step up the energy rectified by thesecond rectifier to the global power maximum value.
 16. The methodaccording to claim 13, further comprising indexing, by the receiver, theMPP value in a look-up table.
 17. The method according to claim 13,further comprising: comparing, by the receiver, the energy from thefirst rectifier to the MPP value; and determining, by the receiver, theoperational instruction based on the comparison.